How to generate dfb file during pluggable database unplug

Hi

While doing pluggable database unplug via dbca, then it will unplug it into xml file, and also generate pluggable database backup file (.dfb).

Container database alert log is as follows:

2019-05-30T18:58:32.842582+03:00alter pluggable database DEVPDB3 CLOSE IMMEDIATEDEVPDB3(4):JIT: pid 26249 requesting stopDEVPDB3(4):Buffer Cache flush started: 4DEVPDB3(4):Buffer Cache flush finished: 4Pluggable database DEVPDB3 closedCompleted: alter pluggable database DEVPDB3 CLOSE IMMEDIATEalter pluggable database DEVPDB3 unplug into '/oracle/19.3/db/assistants/dbca/templates//orcl_DEVPDB3.xml'DEVPDB3(4):Autotune of undo retention is turned on.2019-05-30T18:58:33.820010+03:00DEVPDB3(4):Endian type of dictionary set to little2019-05-30T18:58:33.984989+03:00DEVPDB3(4):Undo initialization recovery: err:0 start: 182293189 end: 182293197 diff: 8 ms (0.0 seconds)DEVPDB3(4):[26249] Successfully onlined Undo Tablespace 2.DEVPDB3(4):Undo initialization online undo segments: err:0 start: 182293197 end: 182293385 diff: 188 ms (0.2 seconds)DEVPDB3(4):Undo initialization finished serial:0 start:182293189 end:182293394 diff:205 ms (0.2 seconds)DEVPDB3(4):Database Characterset for DEVPDB3 is AL32UTF82019-05-30T18:58:36.240996+03:00DEVPDB3(4): AUDSYS.AUD$UNIFIED (SQL_TEXT) - CLOB populatedDEVPDB3(4):JIT: pid 26249 requesting stopDEVPDB3(4):Buffer Cache